Transformer identification

[harry bissell]

The magnetic field will vary by the type of core construction... Toroids
contain the magnetic field the best.  When the magnetic filed is no longer
contained in the core and starts to appear in the air surrounding the
transformer, the core is saturated (a bad thing) this is way over the rating of
the transformer. You want to run a transformer in the linear region of the
curve (normally). Small transformers run hotter because they "push" the core
harder (nearer saturation). Shielded transformers can't work with this method.
:^) Harry

The Dark force of dance wrote:

> Y-ellow Paul 'n'  y'all.
>
> At 06:08 PM 08/11/99 +1000, Paul Perry wrote:
>
> >I suspect he is just going by the weight. The VA depends partly on how hot
> >you are prepared to run the transformer. If you assume that most
> >ordinary laminated transformers are pretty similar in geometry, you cant
> >go far wrong. Especially as all he has to do is guarantee that a
> >particular transformer will give x amps without getting 'too' hot.
> >If he was completely fanatical he could make a load out of old stove
> elements.
>
> Yup that sound furry muff. That's basically how I do it. But then you get
> these weird telecom  transformers. Relatively huge heavy things rated at
> 300mA? Now we can assume that they're seriously over engineered but what
> seems to be the case is that they have huge cores and lots of wire, but
> it's all really thin windings.
>
> Like. Judging from the size and weight you could run at least a 50 watt amp
> from it but you know that's just not going to happen. Which is a bugger
> because I once collected a hell of a lot of 'em with a view to do just
> that. Weren't I disappointed. :(
>
> Another thought had crossed my mind  was  that I'm wondering if you
> couldn't measure the external  magnetic field under load or something. I'm
> not entirely sure how you could do this but it just struck me that the
> apparent field would change under load. And I know transformers have a sag
> in them. though I'm not sure how this would be useful either since it's
> more or less  linear. If  there was a knee at optimum  efficiency or
> something then that might be useful.
>
> It would be nice to work out a way of doing this.
>
> Anyway thanks again.
>
> be absolutely Icebox.
>
>  _ __        _
> | "_ \      | |         batzman at all-electric.com / aek at all-electric.com
> | |_)/  __ _| |_ ____           ALL ELECTRIC KITCHEN
> |  _ \ / _` | __|___ |  The Elementary Urban sanity CD
> | |_) | (_| | |_  / /   out now on Transmission Communications
> |_,__/ \__,_|\__|/ /
>                 / ,__   http://www.all-electric.com
> Goodfortune    |_____|